HTR1B is the G-protein coupled receptor for 5-hydroxytryptamine (serotonin). It functions as a receptor for serotonin, ergot alkaloid derivatives, anxiolytic and antidepressant drugs, and various psychoactive substances. Ligand binding triggers signaling via G-proteins and modulates downstream activity of adenylate cyclase. It plays a role in neural activity, pain perception, mood, and behavior, and plays a role in the vasoconstriction of cerebral arteries. There is evidence that HTR1B is involved in self-renewal of acute myeloid leukemia cells and is differentially expressed versus normal tissue in the disease. In immunohistochemistry of normal tissue, the protein is expressed in a variety of tissues, including various brain regions, subsets of immune cells, the placenta and vessels. References: Physiological Research / Academia Scientiarum Bohemoslovaca. 2011. 60 (1): 15–25, PMID: 20945968; Journal of Neurochemistry. 125 (6): 809–21, PMID 23452061; Leukemia. 2017 Nov;31(11):2288-2302, PMID: 28193998